These landings have one of my favourite ever engineering failures, regarding Venera 14. Venera 13 and 14 were twin landers which landed at the same time on Venu

These landings have one of my favourite ever engineering failures, regarding Venera 14. Venera 13 and 14 were twin landers which landed at the same time on Venus. Both contained a similar science package - including an arm to measure the compressibility of the soil on the surface of Venus. Venera 13's arm functioned properly. Venera 14's returned strange data, which was soon traced to a very simple fault - both Venera landers had a lens cap protecting their sensitive camera equipment on descent. These popped off on landing, and then the spring-loaded instrument arm extended to perform its testing. Venera 13's arm extended into the soil correctly. Venera 14's arm extended directly into its discarded lens cap. Poor Venera 14 travelled millions of kilometers to test the compressibility of a lens cap on the surface of venus. http://www.mentallandscape.com/C_Venera_Perspective.jpg http://www.mentallandscape.com/C_Venera_Perspective.jpg (Venera 14 on right) Venera 14 did also function for almost twice its design lifetime (~57 minutes) so it was a good little probe, but I love to use this little example when talking about reliability engineering.